Osteoarthritis is a type of arthritis that is caused by the breakdown and eventual loss of cartilage in one or more joints. Cartilage is a protein substance that serves as a “cushion” between the bones of the joints. Osteoarthritis is also known as degenerative arthritis. Among the over 100 different types of arthritis conditions, osteoarthritis is the most common, affecting over twenty million people in the United States.
Osteoarthritis often affects synovial joints, such as the knees, hips, fingers, thumbs, neck, and spine. Synovial joints consist of two bone ends covered by articular cartilage. Osteoarthritis may be caused by meniscal or ligament injury, pyogenic infection, ligamentous instability, joint fracture, obesity, or natural degenerative causes.
Severe forms of the disease are extremely disabling and restrict a patient's lifestyle. Patients with osteoarthritis often suffer from depression, anxiety, feelings of helplessness, job limitations, and the inability to perform daily activities. The financial burden resulting from medical treatment and wages lost because of osteoarthritis is often great.
A number of techniques are currently used to treat osteoarthritis. Non-surgical techniques for treating osteoarthritis include weight loss, rest, physical therapy, orthotics, and heat. Weight loss alleviates stress on an affected joint and is sometimes effective in treating osteoarthritis. Short-term rest of an affected joint may be effective in temporarily relieving pain. However, longer periods of rest may result in muscle atrophy and decreased joint mobility. Physical therapy can improve the flexibility and strength of the muscles surrounding an arthritic joint, thus changing the distribution of the stress in the joint and slowing the progression of the disease. Orthotics such as insoles or heeled sport shoes can also improve the distribution of force across an affected joint. Heat applied to an affected joint is sometimes effective in treating osteoarthritis because it may produce analgesia and decrease muscle spasms. However, many of these non-surgical techniques are frequently unsuccessful in treating osteoarthritis. Where these non-surgical techniques are successful, they generally offer only short-term relief.
Pharmacologic therapy for osteoarthritis is primarily used to alleviate the pain associated with osteoarthritis rather than to treat the cause of the disease. Analgesic agents used to treat osteoarthritis include non-steroidal anti-inflammatory drugs such as COX-2 inhibitors (e.g., ViOXX™, Celebrex™). These drugs provide treatment of pain and inflammation in osteoarthritis, but may be of limited efficacy in more severe cases.
Intraarticular injection of corticosteroids or other suitable agents may also be used to treat osteoarthritis. Intraarticular injections may be appropriate when non-steroidal anti-inflammatory dugs (NSAIDs) are insufficient to control the pain symptoms of osteoarthritis. Intraarticular corticosteroids slow catabolism of cartilage and osteophyte formation and have been found to be effective for short-term pain relief.
Surgical interventions for osteoarthritis include arthroscopy, arthroplasty, and chondrocyte grafting. Arthroscopy involves the removal of damaged cartilage and has been widely used for knee osteoarthritis. Arthroscopy offers temporary improvement in some patients. However, some patients do not react well to arthroscopy and their symptoms of osteoarthritis may actually increase.
Chondrocyte grafting involves the implantation of cultivated chondrocytes into a joint to replace damaged cartilage. Chondrocyte grafting is a difficult and costly procedure and often does not successfully alleviate the symptoms of osteoarthritis.
In arthroplasty, a joint that is affected by osteoarthritis is entirely replaced with a prosthetic joint. Arthroplasty is typically targeted towards older patients with modest activity levels due to the limited lifespan of prosthetic joints. Prosthetic joints last approximately ten years and can be replaced a maximum of two times. Hence, arthroplasty is not a viable option for many younger patients with osteoarthritis.
The symptoms of osteoarthritis may also be controlled through the use of a transcutaneous electrical nerve stimulation (TENS) system which masks local pain sensations with a fine tingling sensation. However, TENS devices can produce significant discomfort and can only be used intermittently.